Flame-retardant poly(arylene ether) composition and its use as a covering for coated wire

ABSTRACT

A flame retardant poly(arylene ether) composition is described. In addition to the poly(arylene ether), the composition includes a polyolefin component, and a flame retardant composition that includes a metal dialkyl phosphinate but excludes melamine phosphate, melamine pyrophosphate, and melamine polyphosphate. The polyolefin component can be a polyolefin polymer and/or the polyolefin block of a poly(alkenyl aromatic)-polyolefin block copolymer. The composition is particularly suitable as a replacement for poly(vinyl chloride) in insulation for wire and cable.

BACKGROUND OF THE INVENTION

Poly(arylene ether) resin is a type of plastic known for its excellentwater resistance, dimensional stability, and inherent flame retardancy.Properties such as strength, stiffness, chemical resistance, and heatresistance can be tailored by blending it with various other plastics inorder to meet the requirements of a wide variety of consumer products,for example, plumbing fixtures, electrical boxes, automotive parts, andinsulation for wire and cable.

Poly(vinyl chloride) is currently the commercial dominant material forflame retardant wire and cable insulation. However, poly(vinyl chloride)is a halogenated material. There is mounting concern over theenvironmental impact of halogenated materials, and non-halogenatedalternatives are being sought. There is therefore a strong desire—and insome places a legislative mandate—to replace poly(vinyl chloride) withnon-halogenated polymer compositions.

Recent research has demonstrated that certain halogen-free poly(aryleneether) compositions can possess the physical and flame retardantproperties needed for use as wire and cable insulation. See, forexample, U.S. Patent Application Publication Nos. US 2006/0106139 A1 andUS 2006/0182967 A1 of Kosaka et al. The compositions disclosed in thesereferences can exhibit good flame retardancy and good physicalproperties such as flexibility and tensile strength. However, in someinstances trade-offs in physical properties accompany the relativelylarge amounts of flame retardants required. For example, when the flameretardant composition comprises substantial amounts of a metal hydroxidesuch as magnesium hydroxide, flexibility and proccessability andabrasion resistance are compromised. As another example, when the flameretardant composition comprises substantial amounts of a liquid organicphosphate flame retardant, the flame retardant can migrate to thesurface of the insulation, creating an esthetic problem and, moreimportantly, compromising the flame retardancy of the thermoplasticcomposition. There remains a desire for flame retardant poly(aryleneether) compositions that exhibit an improved balance of flameretardancy, physical properties, and esthetic properties.

BRIEF DESCRIPTION OF THE INVENTION

The above-described and other drawbacks are alleviated by athermoplastic composition, comprising: 20 to 50 weight percent of apoly(arylene ether); 25 to 57 weight percent of total polyolefin;wherein total polyolefin consists of polyolefins and the polyolefincontent of block copolymers comprising a poly(alkenyl aromatic) blockand a polyolefin block; and 3 to 30 weight percent of a flame retardantcomposition comprising a metal dialkyl phosphinate; wherein the flameretardant composition excludes melamine phosphate, melaminepyrophosphate, and melamine polyphosphate; wherein all weight percentsare based on the total weight of the thermoplastic composition; whereinthe poly(arylene ether) and total polyolefin are present in a weightratio of 0.55:1 to 1.2:1; and wherein a test sample coated wire exhibitsa tensile stress at break of at least 10 megapascals, measured at 23° C.according to UL 1581, Section 470, a tensile elongation at break of atleast 100 percent, measured at 23° C. according to UL 1581, Section 470,and a passing flame test rating according to UL 1581, Section 1080,wherein the test sample coated wire consists of an AWG 24 wire having anominal cross sectional area of 0.205 millimeter², and a tubularcovering comprising the thermoplastic composition and having a nominalouter diameter of 2 millimeters.

Another embodiment is an extruded article, comprising: 20 to 50 weightpercent of a poly(arylene ether); 25 to 57 weight percent of totalpolyolefin; wherein total polyolefin consists of polyolefins and thepolyolefin content of block copolymers comprising a poly(alkenylaromatic) block and a polyolefin block; and 3 to 30 weight percent of aflame retardant composition comprising a metal dialkyl phosphinate;wherein the flame retardant composition excludes melamine phosphate,melamine pyrophosphate, and melamine polyphosphate; wherein all weightpercents are based on the total weight of the thermoplastic composition;wherein the poly(arylene ether) and total polyolefin are present in aweight ratio of 0.55:1 to 1.2:1; and wherein a test sample coated wireexhibits a tensile stress at break of at least 10 megapascals, measuredat 23° C. according to UL 1581, Section 470, a tensile elongation atbreak of at least 100 percent, measured at 23° C. according to UL 1581,Section 470, and a passing flame test rating according to UL 1581,Section 1080, wherein the test sample coated wire consists of an AWG 24wire having a nominal cross sectional area of 0.205 millimeter², and atubular covering comprising the thermoplastic composition and having anominal outer diameter of 2 millimeters.

Another embodiment is a coated wire, comprising: a conductor, and acovering disposed on the conductor; wherein the covering comprises acomposition comprising 20 to 50 weight percent of a poly(arylene ether);25 to 57 weight percent of total polyolefin; wherein total polyolefinconsists of polyolefins and the polyolefin content of block copolymerscomprising a poly(alkenyl aromatic) block and a polyolefin block; and 3to 30 weight percent of a flame retardant composition comprising a metaldialkyl phosphinate; wherein the flame retardant composition excludesmelamine phosphate, melamine pyrophosphate, and melamine polyphosphate;wherein all weight percents are based on the total weight of thethermoplastic composition; wherein the poly(arylene ether) and totalpolyolefin are present in a weight ratio of 0.55:1 to 1.2:1; and whereina test sample coated wire exhibits a tensile stress at break of at least10 megapascals, measured at 23° C. according to UL1581, Section 470, atensile elongation at break of at least 100 percent, measured at 23° C.according to UL1581, Section 470, and a passing flame test ratingaccording to UL 1581, Section 1080, wherein the test sample coated wireconsists of an AWG 24 wire having a nominal cross sectional area of0.205 millimeter², and a tubular covering comprising the thermoplasticcomposition and having a nominal outer diameter of 2 millimeters.

These and other embodiments are described in detail below.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have conducted research on poly(arylene ether)compositions for wire and cable insulation. In the course of thatresearch, they have discovered that a particularly desirable andimproved balance of flame retardancy properties, physical properties,and esthetic properties are obtained when a poly(arylene ether)composition comprising very particular component amounts is present. Onesurprising aspect of this discovery is that the improved propertybalance is obtained, in part, by controlling the amount of totalpolyolefin. The term “total polyolefin” includes not only olefinhomopolymers (such as polyethylene, polypropylene, and poly(1-butene),and olefin copolymers (such as linear low-density polyethylene (LLDPE),ethylene-propylene-diene monomer copolymers (EPDM), and the copolymersof butene isomers known as polybutenes), but also the polyolefinsegments of block copolymers (such as the poly(ethylene-butylene)segment of a polystyrene-poly(ethylene-butylene)-polystyrene blockcopolymer). In other words, whereas previous patent documents havedescribed poly(arylene ether)-polyolefin compositions in terms ofseparate amounts of polyolefins and styrenic block copolymer, thepresent inventors have discovered that the total polyolefin content asdefined above is a previously unrecognized result-effective variable inpredicting and controlling flame retardancy properties, physicalproperties, and esthetic properties.

One embodiment is a thermoplastic composition, comprising: 20 to 50weight percent of a poly(arylene ether); 25 to 57 weight percent oftotal polyolefin; wherein total polyolefin consists of polyolefins andthe polyolefin content of block copolymers comprising a poly(alkenylaromatic) block and a polyolefin block; and 3 to 30 weight percent of aflame retardant composition comprising a metal dialkyl phosphinate;wherein the flame retardant composition excludes melamine phosphate,melamine pyrophosphate, and melamine polyphosphate; wherein all weightpercents are based on the total weight of the thermoplastic composition;wherein the poly(arylene ether) and total polyolefin are present in aweight ratio of 0.55:1 to 1.2:1; and wherein a test sample coated wireexhibits a tensile stress at break of at least 10 megapascals, measuredat 23° C. according to UL 1581, Section 470, a tensile elongation atbreak of at least 100 percent, measured at 23° C. according to UL 1581,Section 470, and a passing flame test rating according to UL 1581,Section 1080, wherein the test sample coated wire consists of an AWG 24wire (according to UL1581, 4th Edition, Oct. 31, 2001, Section 20, Table20.1) having a nominal cross sectional area of 0.205 millimeter², and atubular covering comprising the thermoplastic composition and having anominal outer diameter of 2 millimeters. The copper conductor consistsof twenty twisted copper threads, each having a diameter of 0.12millimeter. The passing flame test rating according to UL 1581, Section1080 is assessed according to Section 1080.14. Specifically, the coatedwire passes the test if (1) no specimen shows more than 25 percent ofthe indicator flag burned away or charred after any of the fiveapplications of flame; and (2) no specimen emits flaming or glowingparticles or foaming drops at any time that ignite the cotton, orcontinues to flame longer than 60 seconds after any application of thegas flame; and (3) if any specimen emits flaming or glowing particles orflaming drops at any time that fall outside the area of the testingsurface covered by the cotton and/or that fall onto the wedge or burner,a repeat test according to Section 1080.14 is to be conducted, and noneof the cotton is to ignite in the repeat test and the specimen does notcontinue flaming longer than 60 seconds after any application of the gasflame.

In some embodiments, the test sample coated wire (specifically, itscovering) exhibits a tensile stress at break of 10 to 25 megapascals,specifically 15 to 25 megapascals, more specifically 20 to 25megapascals, measured at 23° C. according to UL1581, Section 470; and atensile elongation at break of 100 to 360 percent, specifically 150 to300 percent, more specifically 200 to 250 percent, measured at 23° C.according to UL1581, Section 470. In some embodiments, the test samplecoated wire further exhibits a heat deformation of 5 to 20 percent,specifically 10 to 15 percent, measured at 121° C. and a 250 gram loadaccording to UL 1580.

The thermoplastic composition comprises a poly(arylene ether). Suitablepoly(arylene ether)s include those comprising repeating structural unitshaving the formula

wherein each occurrence of Z¹ is independently halogen, unsubstituted orsubstituted C₁-C₁₂ hydrocarbyl provided that the hydrocarbyl group isnot tertiary hydrocarbyl, C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy,or C₂-C₁₂ halohydrocarbyloxy wherein at least two carbon atoms separatethe halogen and oxygen atoms; and each occurrence of Z² is independentlyhydrogen, halogen, unsubstituted or substituted C₁-C₁₂ hydrocarbylprovided that the hydrocarbyl group is not tertiary hydrocarbyl, C₁-C₁₂hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, or C₂-C₁₂ halohydrocarbyloxywherein at least two carbon atoms separate the halogen and oxygen atoms.As used herein, the term “hydrocarbyl”, whether used by itself, or as aprefix, suffix, or fragment of another term, refers to a residue thatcontains only carbon and hydrogen. The residue can be aliphatic oraromatic, straight-chain, cyclic, bicyclic, branched, saturated, orunsaturated. It can also contain combinations of aliphatic, aromatic,straight chain, cyclic, bicyclic, branched, saturated, and unsaturatedhydrocarbon moieties. However, when the hydrocarbyl residue is describedas substituted, it may, optionally, contain heteroatoms over and abovethe carbon and hydrogen members of the substituent residue. Thus, whenspecifically described as substituted, the hydrocarbyl residue may alsocontain one or more carbonyl groups, amino groups, hydroxyl groups, orthe like, or it may contain heteroatoms within the backbone of thehydrocarbyl residue. As one example, Z¹ may be a di-n-butylaminomethylgroup formed by reaction of a terminal 3,5-dimethyl-1,4-phenyl groupwith the di-n-butylamine component of an oxidative polymerizationcatalyst.

In some embodiments, the poly(arylene ether) comprises2,6-dimethyl-1,4-phenylene ether units, 2,3,6-trimethyl-1,4-phenyleneether units, or a combination thereof. In some embodiments, thepoly(arylene ether) is a poly(2,6-dimethyl-1,4-phenylene ether).

The poly(arylene ether) can comprise molecules havingaminoalkyl-containing end group(s), typically located in a positionortho to the hydroxy group. Also frequently present aretetramethyldiphenoquinone (TMDQ) end groups, typically obtained from2,6-dimethylphenol-containing reaction mixtures in whichtetramethyldiphenoquinone by-product is present. The poly(arylene ether)can be in the form of a homopolymer, a copolymer, a graft copolymer, anionomer, or a block copolymer, as well as combinations comprising atleast one of the foregoing.

In some embodiments, the poly(arylene ether) has an intrinsic viscosityof 0.1 to 1 deciliter per gram measured at 25° C. in chloroform.Specifically, the poly(arylene ether) intrinsic viscosity may be 0.2 to0.8 deciliter per gram, more specifically 0.3 to 0.6 deciliter per gram,still more specifically 0.4 to 0.5 deciliter per gram.

The thermoplastic composition comprises 20 to 50 weight percent of apoly(arylene ether), based on the total weight of the thermoplasticcomposition. Within this range, the poly(arylene ether) amount can be 30to 47 weight percent, specifically 39 to 47 weight percent.

In addition to the poly(arylene ether), the thermoplastic compositioncomprises 25 to 57 weight percent of total polyolefin. As mentionedabove, the total polyolefin consists of consists of polyolefins and thepolyolefin content of block copolymers comprising a poly(alkenylaromatic) block and a polyolefin block. The term “polyolefins” includesolefin homopolymers. Exemplary homopolymers include polyethylene, highdensity polyethylene (HDPE), medium density polyethylene (MDPE), andisotactic polypropylene. Polyolefins further includes olefin copolymers.Such copolymers include copolymers of ethylene and alpha olefins like1-octene, propylene and 4-methyl-1-pentene as well as copolymers ofethylene and one or more rubbers and copolymers of propylene and one ormore rubbers. Copolymers of ethylene and C₃-C₁₀ monoolefins andnon-conjugated dienes, herein referred to as EPDM copolymers, are alsosuitable. Examples of suitable C₃-C₁₀ monoolefins for EPDM copolymersinclude propylene, 1-butene, 2-butene, 1-pentene, 2-pentene, 1-hexene,2-hexene, 3-hexene, and the like. Suitable dienes include 1,4-hexadieneand monocylic and polycyclic dienes. Mole ratios of ethylene to otherC₃-C₁₀ monoolefin monomers can range from 95:5 to 5:95 with diene unitsbeing present in the amount of from 0.1 to 10 mole percent. EPDMcopolymers can be functionalized with an acyl group or electrophilicgroup for grafting onto the polyphenylene ether as disclosed in U.S.Pat. No. 5,258,455 to Laughner et al. Olefin copolymers further includelinear low density polyethylene (LLDPE). Total polyolefin furtherincludes the polyolefin segments of block copolymers, such as thepoly(ethylene-butylene) segment of apolystyrene-poly(ethylene-butylene)-polystyrene block copolymer, and thepoly(ethylene-propylene) segment of apolystyrene-poly(ethylene-propylene) diblock copolymer.

In some embodiments, the total polyolefin is selected from the groupconsisting of ethylene-octene copolymers, ethylene-butene copolymers,ethylene-propylene copolymers, polypropylenes, polybutenes, thepoly(ethylene-propylene) blocks ofpolystyrene-poly(ethylene-propylene)-polystyrene triblock copolymers,the poly(ethylene-butylene) blocks ofpolystyrene-poly(ethylene-butylene)-polystyrene triblock copolymers, andmixtures thereof. In some embodiments, the total polyolefin is selectedfrom the group consisting of polypropylenes, polybutenes, thepoly(ethylene-propylene) blocks ofpolystyrene-poly(ethylene-propylene)-polystyrene triblock copolymers,the poly(ethylene-butylene) blocks ofpolystyrene-poly(ethylene-butylene)-polystyrene triblock copolymers, andmixtures thereof.

The total polyolefin amount is 25 to 57 weight percent, specifically 30to 50 weight percent, more specifically 35 to 42 weight percent, basedon the total weight of the thermoplastic composition.

It is not just the specific amounts of poly(arylene ether) and totalpolyolefin that are important to achieving the desired properties, theratio of these components is also important. Thus, the poly(aryleneether) and total polyolefin are present in a weight ratio of 0.55:1 to1.2:1, specifically 0.8:1 to 1.2:1, more specifically 1.1:1 to 1.2:1.

As mentioned above in the context of total polyolefin, the thermoplasticcomposition can comprise a block copolymer comprising a poly(alkenylaromatic) block and a polyolefin block. In some embodiments, thepolyolefin block is a poly(conjugated diene) or a hydrogenatedpoly(conjugated diene). The block copolymer may comprise about 15 toabout 80 weight percent of poly(alkenyl aromatic) content and about 20to about 85 weight percent of unhydrogenated or hydrogenatedpoly(conjugated diene) content. In some embodiments, the poly(alkenylaromatic) content is about 20 to 40 weight percent. In otherembodiments, the poly(alkenyl aromatic) content is greater than 40weight percent to about 90 weight percent, specifically about 55 toabout 80 weight percent.

In some embodiments, the block copolymer has a weight average molecularweight of about 3,000 to about 400,000 atomic mass units. The numberaverage molecular weight and the weight average molecular weight can bedetermined by gel permeation chromatography and based on comparison topolystyrene standards. In some embodiments, the block copolymer has aweight average molecular weight of 40,000 to 400,000 atomic mass units,specifically 200,000 to 400,000 atomic mass units, more specifically220,000 to 350,000 atomic mass units. In other embodiments, the blockcopolymer has a weight average molecular weight of 40,000 to less than200,000 atomic mass units, specifically 40,000 to 180,000 atomic massunits, more specifically 40,000 to 150,000 atomic mass units.

The alkenyl aromatic monomer used to prepare the block copolymer canhave the structure

wherein R¹ and R² each independently represent a hydrogen atom, a C₁-C₈alkyl group, or a C₂-C₈ alkenyl group; R³ and R⁷ each independentlyrepresent a hydrogen atom, or a C₁-C₈ alkyl group; and R⁴, R⁵, and R⁶each independently represent a hydrogen atom, a C₁-C₈ alkyl group, or aC₂-C₈ alkenyl group, or R³ and R⁴ are taken together with the centralaromatic ring to form a naphthyl group, or R⁴ and R⁵ are taken togetherwith the central aromatic ring to form a naphthyl group. Specificalkenyl aromatic monomers include, for example, styrene andmethylstyrenes such as alpha-methylstyrene and p-methylstyrene. In someembodiments, the alkenyl aromatic monomer is styrene.

The conjugated diene used to prepare the block copolymer can be a C₄-C₂₀conjugated diene. Suitable conjugated dienes include, for example,1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene,2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like,and combinations thereof. In some embodiments, the conjugated diene is1,3-butadiene, 2-methyl-1,3-butadiene, or a combination thereof. In someembodiments, the conjugated diene consists of 1,3-butadiene.

The block copolymer is a copolymer comprising (A) at least one blockderived from an alkenyl aromatic compound and (B) at least one blockderived from a conjugated diene. In some embodiments, the aliphaticunsaturation in the (B) block is reduced at least 50 percent,specifically at least 70 percent, by hydrogenation. The arrangement ofblocks (A) and (B) includes a linear structure, a grafted structure, anda radial teleblock structure with or without a branched chain. Linearblock copolymers include tapered linear structures and non-taperedlinear structures. In some embodiments, the block copolymer has atapered linear structure. In some embodiments, the block copolymer has anon-tapered linear structure. In some embodiments, the block copolymercomprises a B block that comprises random incorporation of alkenylaromatic monomer. Linear block copolymer structures include diblock (A-Bblock), triblock (A-B-A block or B-A-B block), tetrablock (A-B-A-Bblock), and pentablock (A-B-A-B-A block or B-A-B-A-B block) structuresas well as linear structures containing 6 or more blocks in total of Aand B, wherein the molecular weight of each A block may be the same asor different from that of other A blocks, and the molecular weight ofeach B block may be the same as or different from that of other Bblocks. In some embodiments, the block copolymer is a diblock copolymer,a triblock copolymer, or a combination thereof. In some embodiments, theblock copolymer is a polystyrene-poly(ethylene-butylene)-polystyrenetriblock copolymer.

In some embodiments, the block copolymer excludes the residue ofmonomers other than the alkenyl aromatic compound and the conjugateddiene. In some embodiments, the block copolymer consists of blocksderived from the alkenyl aromatic compound and the conjugated diene. Inthese embodiments it does not comprise grafts formed from these or anyother monomers; it also consists of carbon and hydrogen atoms andtherefore excludes heteroatoms.

In other embodiments, the block copolymer includes the residue of one ormore acid functionalizing agents, such as maleic anhydride.

Methods of preparing block copolymers are known in the art and manyhydrogenated block copolymers are commercially available. Illustrativecommercially available hydrogenated block copolymers include thepolystyrene-poly(ethylene-propylene) diblock copolymers available fromKraton Polymers as Kraton G1701 and G1702; thepolystyrene-poly(ethylene-butylene)-polystyrene triblock copolymersavailable from Kraton Polymers as Kraton G1641, G1650, G1651, G1654,G1657, G1726, G4609, G4610, GRP-6598, RP-6924, MD-6932M, MD-6933, andMD-6939; the polystyrene-poly(ethylene-butylene-styrene)-polystyrene(S-EB/S-S) triblock copolymers available from Kraton Polymers as KratonRP-6935 and RP-6936, thepolystyrene-poly(ethylene-propylene)-polystyrene triblock copolymersavailable from Kraton Polymers as Kraton G1730; the maleicanhydride-grafted polystyrene-poly(ethylene-butylene)-polystyrenetriblock copolymers available from Kraton Polymers as Kraton G1901,G1924, and MD-6684; the maleic anhydride-graftedpolystyrene-poly(ethylene-butylene-styrene)-polystyrene triblockcopolymer available from Kraton Polymers as Kraton MD-6670; thepolystyrene-poly(ethylene-butylene)-polystyrene triblock copolymercomprising 67 weight percent polystyrene available from Asahi KaseiElastomer as TUFTEC H1043; thepolystyrene-poly(ethylene-butylene)-polystyrene triblock copolymercomprising 42 weight percent polystyrene available from Asahi KaseiElastomer as TUFTEC H1051; thepolystyrene-poly(butadiene-butylene)-polystyrene triblock copolymersavailable from Asahi Kasei Elastomer as TUFTEC P1000 and P2000; thepolystyrene-polybutadiene-poly(styrene-butadiene)-polybutadiene blockcopolymer available from Asahi Kasei Elastomer as S.O.E.-SS L601; thehydrogenated radial block copolymers available from Chevron PhillipsChemical Company as K-Resin KK38, KR01, KR03, and KR05; thepolystyrene-poly(ethylene-butylene)-polystyrene triblock copolymercomprising about 60 weight polystyrene available from Kuraray as SEPTONS8104; the polystyrene-poly(ethylene-ethylene/propylene)-polystyrenetriblock copolymers available from Kuraray as SEPTON S4044, S4055,S4077, and S4099; and thepolystyrene-poly(ethylene-propylene)-polystyrene triblock copolymercomprising about 65 weight percent polystyrene available from Kuraray asSEPTON S2104. Mixtures of two of more block copolymers may be used.Illustrative commercially available unhydrogenated block copolymersinclude the KRATON® D series polymers, including KRATON® D1101 andD1102, from Kraton Polymers, and the styrene-butadiene radial teleblockcopolymers available as, for example, K-RESIN KR01, KR03, KR05, and KR10sold by Chevron Phillips Chemical Company.

The thermoplastic composition can comprise the block copolymer in anamount of 15 to 50 weight percent, specifically 22 to 43 weight percent,more specifically 30 to 40 weight percent, based on the total weight ofthe thermoplastic composition.

In addition to the poly(alkenyl aromatic) blocks present in the blockcopolymer, the thermoplastic composition can comprise homopolymers andcopolymers of alkenyl aromatic monomers. As used herein the term“copolymer of alkenyl aromatic monomers” refers to a copolymer ofmonomers consisting of two or more different alkenyl aromatic monomers.Homopolymers of alkenyl aromatic monomers include polystyrenes,including atactic and syndiotactic polystyrenes. Copolymers of alkenylaromatic monomers include copolymers of two or more monomers selectedfrom the group consisting of styrene, methylstyrenes, andt-butylstyrenes. The homopolymers and copolymers of alkenyl aromaticmonomers, when present, can be used in an amount of 2 to 20 weightpercent, specifically 5 to 15 weight percent, based on the total weightof the thermoplastic composition.

The total poly(alkenyl aromatic) content of the thermoplasticcomposition consists of poly(alkenyl aromatic)s (that is, homopolymersand copolymers of alkenyl aromatic monomers) and the poly(alkenylaromatic) content of block copolymers comprising a poly(alkenylaromatic) block and a polyolefin block. In some embodiments, this totalpoly(alkenyl aromatic) content is 3 to 20 weight percent, specifically 8to 20 weight percent, more specifically 9 to 18 weight percent, morespecifically 11 to 16 weight percent, based on the total weight of thethermoplastic composition.

In addition to the poly(arylene ether) and the total polyolefin, thethermoplastic composition comprises a flame retardant composition. Theflame retardant composition comprises a metal dialkyl phosphinate andexcludes melamine phosphate, melamine pyrophosphate, and melaminepolyphosphate. In this context, “excludes” means that the flameretardant composition (and therefore the thermoplastic composition)comprises less than 0.5 weight percent of melamine phosphate, melaminepyrophosphate, melamine polyphosphate, or a mixture thereof, wherein allweight percents are based on the total weight of the thermoplasticcomposition. In some embodiments, the flame retardant compositioncomprises less than 0.1 weight percent of melamine phosphate, melaminepyrophosphate, melamine polyphosphate, or a mixture thereof, wherein allweight percents are based on the total weight of the thermoplasticcomposition. In some embodiments, the flame retardant compositioncomprises no intentionally added melamine phosphate, melaminepyrophosphate, or melamine polyphosphate.

As used herein, the term “metal dialkyl phosphinate” refers to a saltcomprising at least one metal cation and at least one dialkylphosphinate anion. In some embodiments, the metal dialkyl phosphinatehas the formula

wherein R¹ and R² are each independently C₁-C₆ allyl; M is calcium,magnesium, aluminum, or zinc; and d is 2 or 3. Examples of R¹ and R²include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl,n-pentyl, and phenyl. In some embodiments, R¹ and R² are ethyl, M isaluminum, and d is 3 (that is, the metal dialkyl phosphinate is aluminumtris(diethyl phosphinate)).

In some embodiments, the metal dialkyl phosphinate is in particulateform. The metal dialkyl phosphinate particles may have a median particlediameter (D50) less than or equal to 40 micrometers, or, morespecifically, a D50 less than or equal to 30 micrometers, or, even morespecifically, a D50 less than or equal to 25 micrometers. Additionally,the metal dialkyl phosphinate may be combined with a polymer, such as apoly(arylene ether), a polyolefin, a polyamide, a block copolymer, orcombination thereof, to form a masterbatch. The metal dialkylphosphinate masterbatch comprises the metal dialkyl phosphinate in anamount greater than is present in the thermoplastic composition.Employing a masterbatch for the addition of the metal dialkylphosphinate to the other components of the thermoplastic composition canfacilitate addition and improve distribution of the metal dialkylphosphinate.

In some embodiments, the flame retardant composition consists of themetal dialkyl phosphinate.

In other embodiments, flame retardant composition further comprises anadditional flame retardant selected from the group consisting of triarylphosphates (especially triaryl phosphates that are liquids at a pressureof one atmosphere and at least one temperature in the range 25 to 50°C.), zinc borate, magnesium hydroxide, and mixtures thereof. Whenpresents, such additional flame retardants can be used in an amount suchthat the total flame retardant composition is less than or equal to 30weight percent based on the total weight of the thermoplasticcomposition.

The composition comprises the flame retardant composition in an amountof 3 to 30 weight percent, specifically 4 to 20 weight percent, morespecifically 4 to 10 weight percent, even more specifically 4 to 8weight percent, still more specifically 4 to 6 weight percent, based onthe total weight of the thermoplastic composition.

In some embodiments, the thermoplastic composition further comprises aflow promoting resin to improve the processing characteristics of thethermoplastic composition. The flow promoting resin has a glasstransition temperature or a melting temperature of 30 to 175° C.,specifically 50 to 170° C., more specifically 70 to 165° C., morespecifically 100 to 160° C., even more specifically 100 to 155° C.Suitable polymer resins include, for example, polystyrenes, hydrocarbonwaxes, hydrocarbon resins, fatty acids, polyolefins, polyesters,fluoropolymers, epoxy resins, phenolic resins, rosins and rosinderivatives, terpene resins, acrylate resins, and combinations thereof.When the flow promoting resin is a polyolefin, the thermoplasticcomposition comprises at least one other polyolefin component.

The thermoplastic composition may, optionally, further comprise variousadditives known in the thermoplastics art. For example, thethermoplastic composition may, optionally, further comprise an additivechosen from stabilizers, mold release agents, processing aids, dripretardants, nucleating agents, UV blockers, dyes, pigments,antioxidants, anti-static agents, blowing agents, mineral oil, metaldeactivators, antiblocking agents, nanoclays, and the like, andcombinations thereof.

In some embodiments, the thermoplastic composition excludes any polymernot described herein as required or optional. In some embodiments, thethermoplastic composition excludes any flame retardant not describedherein as required or optional. In some embodiments, the thermoplasticcomposition excludes fillers.

In one embodiment, the thermoplastic composition comprises 39 to 47weight percent of the poly(arylene ether), wherein the poly(aryleneether) is a poly(2,6-dimethyl-1,4-phenylene ether) having an intrinsicviscosity of 0.3 to 0.6 deciliter per gram measured in chloroform at 25°C.; 35 to 42 weight percent of total polyolefin weight percent of totalpolyolefin, wherein the total polyolefin comprises polypropylene,polybutene, ethylene-propylene copolymer, a poly(ethylene-co-propylene)block of a block copolymer comprising a polystyrene block and apoly(ethylene-co-propylene) block, and a poly(ethylene-co-butylene)block of a block copolymer comprising a polystyrene block and apoly(ethylene-co-butylene) block; and 4 to 10 weight percent of theflame retardant composition consisting of aluminum tris(diethylphosphinate); wherein the poly(arylene ether) and total polyolefin arepresent in a weight ratio of 0.9 to 1.2; and wherein the test samplecoated wire exhibits a tensile stress at break of 10 to 25 megapascals,measured at 23° C. according to UL1581, Section 470, a tensileelongation at break of 150 to 300 percent, measured at 23° C. accordingto UL1581, Section 470, and a passing flame test rating according to UL1581, Section 1080, wherein the test sample coated wire consists of anAWG 24 wire having a nominal cross sectional area of 0.205 millimeter²,and a tubular covering comprising the thermoplastic composition andhaving a nominal outer diameter of 2 millimeters.

As the composition is defined as comprising multiple components, it willbe understood that each component is chemically distinct, particularlyin the instance that a single chemical compound may satisfy thedefinition of more than one component.

The preparation of the compositions of the present invention is normallyachieved by melt blending the ingredients under conditions for theformation of an intimate blend. Such conditions often include mixing insingle-screw or twin-screw type extruders or similar mixing devices thatcan apply a shear to the components.

The thermoplastic composition is well suited for use in fabricatingarticles via extrusion molding. Thus, one embodiment is an extrudedarticle, comprising: 20 to 50 weight percent of a poly(arylene ether);25 to 57 weight percent of total polyolefin; wherein total polyolefinconsists of polyolefins and the polyolefin content of block copolymerscomprising a poly(alkenyl aromatic) block and a polyolefin block; and 3to 30 weight percent of a flame retardant composition comprising a metaldialkyl phosphinate; wherein the flame retardant composition excludesmelamine phosphate, melamine pyrophosphate, and melamine polyphosphate;wherein all weight percents are based on the total weight of thethermoplastic composition; wherein the poly(arylene ether) and totalpolyolefin are present in a weight ratio of 0.55:1 to 1.2:1; and whereina test sample coated wire exhibits a tensile stress at break of at least10 megapascals, measured at 23° C. according to UL 1581, Section 470, atensile elongation at break of at least 100 percent, measured at 23° C.according to UL 1581, Section 470, and a passing flame test ratingaccording to UL 1581, Section 1080, wherein the test sample coated wireconsists of an AWG 24 wire having a nominal cross sectional area of0.205 millimeter², and a tubular covering comprising the thermoplasticcomposition and having a nominal outer diameter of 2 millimeters. Insome embodiments of the extrude article, the test sample coated wireexhibits a tensile stress at break of 10 to 25 megapascals, specifically15 to 25 megapascals, more specifically 20 to 25 megapascals, measuredat 23° C. according to UL1581, Section 470; and a tensile elongation atbreak of 100 to 360 percent, specifically 150 to 300 percent, morespecifically 200 to 25 percent, measured at 23° C. according to UL1581,Section 470. In some embodiments of the extruded article, the flameretardant composition consists of the metal dialkyl phosphinate. In someembodiments, the extruded article is in the form of a hollow tube. Insome embodiments, the extruded article is in the form of a tubularcovering surrounding a core of an electrically conducting or lightconducting medium.

In some embodiments of the extruded article, the thermoplasticcomposition comprises 39 to 47 weight percent of the poly(aryleneether), wherein the poly(arylene ether) is apoly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic viscosity of0.3 to 0.6 deciliter per gram measured in chloroform at 25° C.; 35 to 42weight percent of total polyolefin weight percent of total polyolefin,wherein the total polyolefin comprises polypropylene, polybutene,ethylene-propylene copolymer, a poly(ethylene-co-propylene) block of ablock copolymer comprising a polystyrene block and apoly(ethylene-co-propylene) block, and a poly(ethylene-co-butylene)block of a block copolymer comprising a polystyrene block and apoly(ethylene-co-butylene) block; and 4 to 10 weight percent of theflame retardant composition consisting of aluminum tris(diethylphosphinate); wherein the poly(arylene ether) and total polyolefin arepresent in a weight ratio of 0.9 to 1.2; and wherein the test samplecoated wire exhibits a tensile stress at break of 10 to 25 megapascals,measured at 23° C. according to UL1581, Section 470, and a tensileelongation at break of 150 to 300 percent, measured at 23° C. accordingto UL1581, Section 470.

The thermoplastic composition is particularly suited for use in thefabrication of insulation for wire and cable. Methods of fabricatingcoated wire are known in the art and described, for example, in U.S.Patent Application Publication No. US 2006/0131052 A1 of Mhetar et al.Thus, one embodiment is a coated wire, comprising: a conductor, and acovering disposed on the conductor; wherein the covering comprises acomposition comprising 20 to 50 weight percent of a poly(arylene ether);25 to 57 weight percent of total polyolefin; wherein total polyolefinconsists of polyolefins and the polyolefin content of block copolymerscomprising a poly(alkenyl aromatic) block and a polyolefin block; and 3to 30 weight percent, specifically 4 to 30 weight percent, of a flameretardant composition comprising a metal dialkyl phosphinate; whereinthe flame retardant composition excludes melamine phosphate, melaminepyrophosphate, and melamine polyphosphate; wherein all weight percentsare based on the total weight of the thermoplastic composition; whereinthe poly(arylene ether) and total polyolefin are present in a weightratio of 0.55:1 to 1.2:1; and wherein a test sample coated wire exhibitsa tensile stress at break of at least 10 megapascals, measured at 23° C.according to UL1581, Section 470, a tensile elongation at break of atleast 100 percent, measured at 23° C. according to UL1581, Section 470,and a passing flame test rating according to UL 1581, Section 1080,wherein the test sample coated wire consists of an AWG 24 wire having anominal cross sectional area of 0.205 millimeter², and a tubularcovering comprising the thermoplastic composition and having a nominalouter diameter of 2 millimeters. In some embodiments of the coated wire,the test sample coated wire exhibits a tensile stress at break of 10 to25 megapascals, specifically 15 to 25 megapascals, more specifically 20to 25 megapascals, measured at 23° C. according to UL1581, Section 470;and a tensile elongation at break of 100 to 360 percent, specifically150 to 300 percent, more specifically 200 to 250 percent, measured at23° C. according to UL1581, Section 470. In some embodiments of thecoated wire, the flame retardant composition consists of the metaldialkyl phosphinate. In some embodiments of the coated wire, thethermoplastic composition comprises 39 to 47 weight percent of thepoly(arylene ether), wherein the poly(arylene ether) is apoly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic viscosity of0.3 to 0.6 deciliter per gram measured in chloroform at 25° C.; 35 to 42weight percent of total polyolefin weight percent of total polyolefin,wherein the total polyolefin comprises polypropylene, polybutene,ethylene-propylene copolymer, a poly(ethylene-co-propylene) block of ablock copolymer comprising a polystyrene block and apoly(ethylene-co-propylene) block, and a poly(ethylene-co-butylene)block of a block copolymer comprising a polystyrene block and apoly(ethylene-co-butylene) block; and 4 to 10 weight percent of theflame retardant composition consisting of aluminum tris(diethylphosphinate); wherein the poly(arylene ether) and total polyolefin arepresent in a weight ratio of 0.9 to 1.2; and wherein the test samplecoated wire exhibits a tensile stress at break of 10 to 25 megapascals,measured at 23° C. according to UL1581, Section 470, and a tensileelongation at break of 150 to 300 percent, measured at 23° C. accordingto UL1581, Section 470. It will be understood that the configuration anddimension of the coated wire claimed are not limited to those of thetest sample coated wire for which property values are specified. Forexample, the coated wire can have a conductor with the dimensionsspecified in UL 1581, Section 20, Table 20.1 for AWG 35 to AWG 10. Asanother example, the covering disposed on the conductor can have athickness of 0.2 to 1 millimeter.

The invention is further illustrated by the following non-limitingexamples.

EXAMPLES 1-8 COMPARATIVE EXAMPLES 1 AND 2

Components used to form the melt-blended thermoplastic compositions aredescribed in Table 1.

TABLE 1 Material Description PPE 0.46 Poly(2,6-dimethyl-1,4-phenyleneether), CAS Reg. No. 25134-01-4, having an intrinsic viscosity of 0.46deciliter per gram measured in chloroform at 25° C.; obtained as PPO 646from GE Plastics POE I Copolymer of ethylene and 1-octene, CAS Reg. No.26221-73-8, having a melt flow rate of about 1.1 decigrams per minutemeasured according to ISO 1133 at 190° C. and a load of 2.16 kilograms;obtained as EXACT 8201 from ExxonMobil Chemical POE II Copolymer ofethylene and 1-octene, CAS Reg. No. 26221-73-8, having a melt flow rateof about 1.0 decigrams per minute measured according to ISO 1133 at 190°C. and a load of 2.16 kilograms; obtained as EXACT 8210 from ExxonMobilChemical TPE Thermoplastic elastomers containingpoly(styrene-ethylene/butylene-styrene) triblock copolymer (CAS Reg. No.66070- 58-4), poly(styrene-ethylene/propylene-styrene) triblockcopolymer (CAS Reg. No. 68648-89-5), propylene homopolymer (CAS Reg. No.9003-07-0), ethylene-propylene copolymer (CAS. Reg. No. 9010-79-1),mineral oil (CAS Reg. No. 72623-83-7), and calcium carbonate (CAS Reg.No. 471-34-1); obtained as Sumitomo TPE-SB 2400 from Sumitomo ChemicalCol, Ltd. SEBS I Poly(styrene-ethylene/butylene-styrene) triblockcopolymer, CAS Reg. No. 66070-58-4, having a polystyrene content of 40weight percent, obtained as Kraton RP6936 from Kraton Polymers Ltd. SEBSII Poly(styrene-ethylene/butylene-styrene) triblock copolymer, CAS Reg.No. 66070-58-4, having a polystyrene content of 30%; obtained as KratonG1650 from Kraton Polymers Ltd. Polybutene Polybutene, CAS Reg. No.9003-29-6, having a number average molecular weight of 800 grams permole, a polydispersity index of 1.60; obtained as Indopol H-50 from BPChemical. DEPAL Aluminum tris(diethyl phosphinate), CAS Reg. No.225789-38-8; obtained as OP 930 or OP 1230 from Clariant

Specific compositions are detailed in Table 3, where component amountsare expressed in parts by weight except where specified as weightpercent, in which case the weight percent values are based on the totalweight of the thermoplastic composition. In Table 3, “wt % PO” refers tothe weight percent of total equivalent polyolefin. Total equivalentpolyolefin is the sum of copolymers of ethylene and 1-octene,polypropylene, polybutene, ethylene/butylene blocks andethylene/propylene blocks and propylene homopolymer andethylene-propylene copolymer contributed by the thermoplastic elastomer,and ethylene-butylene blocks contributed by thepoly(styrene-ethylene/butylene-styrene) triblock copolymers. Also inTable 3, “PPE/PO” refers to the weight ratio of poly(arylene ether) tototal equivalent polyolefin.

Compositions were blended on a 37-millimeter inner diameter twin-screwextruder with twelve zones. The extruder was operated at a screwrotation rate of 450 rotations per minute with temperatures of 225° C.in zone 1, 245° C. in zones 2-12, and 255° C. at the die. All componentswere added at the feed throat.

The “composition properties” in Table 3 were determined as follows. Testarticles were injection molded using a barrel temperature of 250° C. anda mold temperature of 40° C. Flammability was determined using the UL 94Vertical Burning Flame Test using a sample thickness of 3.0 or 6.4millimeters. Tensile stress at break and tensile elongation weremeasured at 23° C. according to ASTM D638. Flexural modulus was measuredat 23° C. according to ASTM D790.

The “wire properties” in Table 3 were determined as follows. Test samplecoated wires were prepared using the extrusion coating parameters shownin Table 2.

TABLE 2 Wire Coating Extrusion Parameters Typical Value Units DryingTemperature 60-85 ° C. Drying Time 12 hrs Maximum Moisture Content 0.02% Extruder Length/Diameter Ratio (L/D) 22:1 to 26:1 — Screw speed 15-85rpm Feed Zone Temperature 180-250 ° C. Middle Zone Temperature 220-270 °C. Head Zone Temperature 220-270 ° C. Neck Temperature 220-270 ° C.Cross-head Temperature 220-270 ° C. Die Temperature 220-270 ° C. MeltTemperature 220-270 ° C. Conductor Pre-heat Temperature  25-150 ° C.Screen Pack 150-100 μm Cooling Water Air Gap 100-200 mm Water BathTemperature 15-80 ° C.

The flame retardancy rating “UL1581 VW-1 rating” and the flame out time“VW1, FOT (sec)” were measured according to UL 1581, Section 1080 (VW-1Vertical Specimen). Tensile stress at break, expressed in megapascals,and tensile elongation at break, expressed in percent, were measured at23° C. according to UL1581, Section 470.

TABLE 3 Ex. 1 Ex. 2 Ex. 3 Ex. 4 C. Ex. 1 Ex. 5 Ex. 6 COMPOSITIONS PPE 3230 30 30 30 30 38 POE I — 16 19 22 25 25 — POE II — 16 19 22 25 25 — TPE15.5 — — — — 14 14 Polybutene 7 — — — — 8 8 SEBS I 24 — — — — 30 30 SEBSII — 10 10 10 10 — — DEPAL 20 28 22 16 10 10 8 total all components 98.5100 100 100 100 100 100 wt % PO 35.8 39.0 45.0 51.0 57.0 38.5 38.5 wt %PPE 32.5 30.0 30.0 30.0 30.0 38.0 40.0 PPE/PO 0.91 0.77 0.67 0.59 0.530.99 1.04 COMPOSITION PROPERTIES Shore A hardness 79.9 94.9 92.7 91.889.9 75.4 77.1 Flexural modulus (MPa) 29.7 240 123 78.5 43.3 12.9 14.7Tensile stress at break (MPa) 9.62 11.3 13.1 14.4 15.8 12 12.4 Tensileelongation (%) 190 180 290 350 447 249 246 UL 94 rating at 3 mm V1 FailFail Fail Fail Fail Fail FOT at 3 mm (sec) 14.1 35.5 NA NA NA 23.4 29.7UL 94 rating at 6.4 mm NA NA Fail Fail Fail Fail Fail FOT at 6.4 mm(sec) NA NA NA NA NA 26.4 24.6 WIRE PROPERTIES UL1581 VW-1 rating PassNA Pass Pass Fail Pass Pass Tensile stress at break (MPa) 15.8 NA 20.421.1 20 19.7 18.8 Tensile elongation (%) 245 NA 287 304 352 279 232 Heatdeformation at 121° C./ 15 NA NA NA NA 19.0 15.6 250 g (%) Ex. 7 Ex. 8C. Ex. 2 COMPOSITIONS PPE 42 44 46 POE I — — — POE II — — — TPE 14 14 14Polybutene 8 8 8 SEBS I 30 30 30 SEBS II — — — DEPAL 6 4 2 total allcomponents 100 100 100 wt % PO 38.5 38.5 38.5 wt % PPE 42.0 44.0 46.0PPE/PO 1.09 1.14 1.19 COMPOSITION PROPERTIES Shore A hardness 78.0 78.779.9 Flexural modulus (MPa) 11.6 13.1 12.1 Tensile stress at break (MPa)12.4 11.5 11.4 Tensile elongation (%) 242 175 168 UL 94 rating at 3 mmFail Fail Fail FOT at 3 mm (sec) 58.08 NA NA UL 94 rating at 6.4 mm FailFail Fail FOT at 6.4 mm (sec) 32.21 NA NA WIRE PROPERTIES UL1581 VW-1rating Pass Pass Fail Tensile stress at break (MPa) 21.1 25 24.9 Tensileelongation (%) 237 245 240 Heat deformation at 14.3 13.4 9.8 121° C./250g (%)

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Further, it should further be noted that the terms “first,”“second,” and the like herein do not denote any order, quantity, orimportance, but rather are used to distinguish one element from another.The modifier “about” used in connection with a quantity is inclusive ofthe stated value and has the meaning dictated by the context (e.g., itincludes the degree of error associated with measurement of theparticular quantity).

1. A thermoplastic composition, comprising: 20 to 50 weight percent of apoly(arylene ether); 25 to 57 weight percent of total polyolefin;wherein said polyolefin consists of polyolefins and the polyolefincontent of block copolymers comprising a poly(alkenyl aromatic) blockand a polyolefin block; and 3 to 30 weight percent of a flame retardantcomposition comprising Aluminum tris(diethyl phosphinate); wherein theflame retardant composition excludes melamine phosphate, melaminepyrophosphate, and melamine polyphosphate; wherein all weight percentsare based on the total weight of the thermoplastic composition; whereinthe poly(arylene ether) and total polyolefin are present in a weightratio of 0.55:1 to 1.2:1; and wherein a test sample coated wire exhibitsa tensile stress at break of at least 10 megapascals, measured at 23° C.according to UL 1581, Section 470, a tensile elongation at break of atleast 100 percent, measured at 23° C. according to UL 1581, Section 470,and a passing flame test rating according to UL 1581, Section 1080,wherein the test sample coated wire consists of an AWG 24 wire having anominal cross sectional area of 0.205 millimeter², and a tubularcovering comprising the thermoplastic composition and having a nominalouter diameter of 2 millimeters.
 2. The thermoplastic composition ofclaim 1, wherein the test sample coated wire exhibits a tensile stressat break of 10 to 25 megapascals, measured at 23° C. according toUL1581, Section 470, and a tensile elongation at break of 100 to 360percent, measured at 23° C. according to UL1581, Section
 470. 3. Thethermoplastic composition of claim 1, wherein the test sample coatedwire further exhibits a heat deformation of 5 to 20 percent, measured at121° C. and a 250 gram load according to UL
 1580. 4. The thermoplasticcomposition of claim 1, wherein the flame retardant composition consistsof aluminum tris(diethyl phosphinate).
 5. The thermoplastic compositionof claim 1, further comprising 3 to 20 weight percent of totalpoly(alkenyl aromatic); wherein said total poly(alkenyl aromatic)consists of poly(alkenyl aromatic)s and the poly(alkenyl aromatic)content of block copolymers comprising a poly(alkenyl aromatic) blockand a polyolefin block.
 6. The thermoplastic composition of claim 1,wherein the thermoplastic composition comprises 39 to 47 weight percentof the poly(arylene ether); wherein the poly(arylene ether) is apoly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic viscosity of0.3 to 0.6 deciliter per gram measured in chloroform at 25° C.; whereinthe thermoplastic composition comprises 35 to 42 weight percent of totalpolyolefin; wherein the total polyolefin is selected from the groupconsisting of polypropylene, polybutene, ethylene-propylene copolymer, apoly(ethylene-propylene) block of a block copolymer comprising apolystyrene block and a poly(ethylene-propylene) block, and apoly(ethylene-butylene) block of a block copolymer comprising apolystyrene block and a poly(ethylene-butylene) block; wherein thethermoplastic composition comprises 4 to 10 weight percent of the flameretardant composition consisting of aluminum tris(diethyl phosphinate);wherein the poly(arylene ether) and total polyolefin are present in aweight ratio of 0.9 to 1.2; and wherein the test sample coated wireexhibits a tensile stress at break of 10 to 25 megapascals, measured at23° C. according to UL1581, Section 470, and a tensile elongation atbreak of 150 to 300 percent, measured at 23° C. according to UL1581,Section
 470. 7. An extruded article, comprising a thermoplasticComposition comprising: 20 to 50 weight percent of a poly(aryleneether); 25 to 57 weight percent of total polyolefin; wherein said totalpolyolefin consists of polyolefins and the polyolefin content of blockcopolymers comprising a poly(alkenyl aromatic) block and a polyolefinblock; and 3 to 30 weight percent of a flame retardant compositionaluminum tris(diethyl phosphinate); wherein the flame retardantcomposition excludes melamine phosphate, melamine pyrophosphate, andmelamine polyphosphate; wherein all weight percents are based on thetotal weight of the thermoplastic composition; wherein the poly(aryleneether) and total polyolefin are present in a weight ratio of 0.55:1 to1.2:1; and wherein a test sample coated wire exhibits a tensile stressat break of at least 10 megapascals, measured at 23° C. according to UL1581, Section 470, a tensile elongation at break of at least 100percent, measured at 23° C. according to UL 1581, Section 470, and apassing flame test rating according to UL 1581, Section 1080, whereinthe test sample coated wire consists of an AWG 24 wire having a nominalcross sectional area of 0.205 millimeter², and a tubular coveringcomprising the thermoplastic composition and having a nominal outerdiameter of 2 millimeters.
 8. The extruded article of claim 7, whereinthe test sample coated wire exhibits a tensile stress at break of 10 to25 megapascals, measured at 23° C. according to UL1581, Section 470, anda tensile elongation at break of 100 to 360 percent, measured at 23° C.according to UL1581, Section
 470. 9. The extruded article of claim 7,wherein the flame retardant composition consists of aluminumtris(diethyl phosphinate).
 10. The extruded article of claim 7, whereinthe thermoplastic composition comprises 39 to 47 weight percent of thepoly(arylene ether); wherein the poly(arylene ether) is apoly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic viscosity of0.3 to 0.6 deciliter per gram measured in chloroform at 25° C.; whereinthe thermoplastic composition comprises 35 to 42 weight percent of totalpolyolefin; wherein the total polyolefin is selected from a groupconsisting of polypropylene, polybutene, ethylene-propylene copolymer, apoly(ethylene-propylene) block of a block copolymer comprising apolystyrene block and a poly(ethylene-propylene) block, and apoly(ethylene-butylene) block of a block copolymer comprising apolystyrene block and a poly(ethylene-butylene) block; wherein thethermoplastic composition comprises 4 to 10 weight percent of the flameretardant composition consisting of aluminum tris(diethyl phosphinate);wherein the poly(arylene ether) and total polyolefin are present in aweight ratio of 0.9 to 1.2; and wherein the test sample coated wireexhibits a tensile stress at break of 10 to 25 megapascals, measured at23° C. according to UL1581, Section 470, and a tensile elongation atbreak of 150 to 300 percent, measured at 23° C. according to UL1581,Section
 470. 11. A coated wire, comprising: a conductor, and a coveringdisposed on the conductor; wherein the covering comprises a compositioncomprising 20 to 50 weight percent of a poly(arylene ether); 25 to 57weight percent of total polyolefin; wherein said total polyolefinconsists of polyolefins and the polyolefin content of block copolymerscomprising a poly(alkenyl aromatic) block and a polyolefin block; and 3to 30 weight percent of a flame retardant composition comprising a metaldialkyl phosphinate; wherein the flame retardant composition excludesmelamine phosphate, melamine pyrophosphate, and melamine polyphosphate;wherein all weight percents are based on the total weight of thethermoplastic composition; wherein the poly(arylene ether) and totalpolyolefin are present in a weight ratio of 0.55:1 to 1.2:1; and whereina test sample of said coated wire exhibits a tensile stress at break ofat least 10 megapascals, measured at 23° C. according to UL1581, Section470, a tensile elongation at break of at least 100 percent, measured at23° C. according to UL1581, Section 470, and a passing flame test ratingaccording to UL 1581, Section 1080, wherein the test sample coated wireconsists of an AWG 24 wire having a nominal cross sectional area of0.205 millimeter², and said covering having a nominal outer diameter of2 millimeters.
 12. The coated wire of claim 11, wherein the test samplecoated wire exhibits a tensile stress at break of 10 to 25 megapascals,measured at 23° C. according to UL1581, Section 470, and a tensileelongation at break of 100 to 360 percent, measured at 23° C. accordingto UL1581, Section
 470. 13. The coated wire of claim 11, wherein theflame retardant composition consists of the metal dialkyl phosphinate.14. The coated wire of claim 11, wherein the thermoplastic compositioncomprises 39 to 47 weight percent of the poly(arylene ether); whereinthe poly(arylene ether) is a poly(2,6-dimethyl-1,4-phenylene ether)having an intrinsic viscosity of 0.3 to 0.6 deciliter per gram measuredin chloroform at 25° C.; wherein the thermoplastic composition comprises35 to 42 weight percent of said total polyolefin; wherein the totalpolyolefin is selected from the group consisting of polypropylene,polybutene, ethylene-propylene copolymer, a poly(ethylene-propylene)block of a block copolymer comprising a polystyrene block and apoly(ethylene-propylene) block, and a poly(ethylene-butylene) block of ablock copolymer comprising a polystyrene block and apoly(ethylene-butylene) block; wherein the thermoplastic compositioncomprises 4 to 10 weight percent of the flame retardant compositionconsisting of aluminum tris(diethyl phosphinate); wherein thepoly(arylene ether) and total polyolefin are present in a weight ratioof 0.9 to 1.2; and wherein the test sample of said coated wire exhibitsa tensile stress at break of 10 to 25 megapascals, measured at 23° C.according to UL1581, Section 470, and a tensile elongation at break of150 to 300 percent, measured at 23° C. according to UL1581, Section 470.15. The coated wire of claim 11, wherein the metal dialkyl phosphinatecomprises aluminum tris(diethyl phosphinate).